JPH1076806A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress permeation of moisture and oxygen around a body ply material without changing its thickness in total and productivity greatly by providing an inner liner layer on an inner side of the body ply material with a specific structure. SOLUTION: In a gas permeation prevention layer (inner liner layer 10) which prevents the entry of gas into a body ply material 3 of a pneumatic tire, for example, three matrix rubber layers A (A layer) A1 to A3 in which polymer having low reactivity with gas and high resistance against gas permeation are matrixed and three gas trap layers B (B layer) B1 to B3 which have low resistance against gas permeation and absorb and trap gas are bonded alternately like a sandwich, and an air side which becomes an innermost layer is A layer A1 . Since oxygen and moisture which are suppressed in A layer A1 and enter gradually are trapped at one end in a layer of B layer B1 which absorbs oxygen and moisture and furthermore, its permeation is suppressed in A layer A2 , the co-existence of them in B layer B1 is forced and they are accumulated and contained in B layer B1 greatly. This action is repeated one after another among A2 and B2 and A3 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire using a steel cord as a body ply material (carcass material), and more particularly to a pneumatic tire with improved durability.

[0002]

2. Description of the Related Art Conventionally, in the field of pneumatic tires such as pneumatic radial tires using a steel cord as a body ply material, a steel cord has a property of being easily corroded significantly in the coexistence of moisture and oxygen; There are two fundamental weaknesses in that the adhesion of rubber / steel (brass plating) is extremely reduced, and this has been a bottleneck in improving the durability of pneumatic tires. For this reason, steel cords and rubber compounds have been devised to improve corrosion resistance and moisture-resistant adhesive deterioration, etc.
Attempts have been made to overcome this weakness.

[0003] However, there is a limit in improving the corrosion fatigue resistance of the steel cord itself, and there is a limit in preventing corrosion by excluding the corrosion accelerating substance in the rubber compound. An important issue is how to prevent intrusion into the body ply material supporting the tire as a pressure vessel, particularly the tire as a pressure vessel.

From this viewpoint, in many pneumatic radial tires and the like, in particular, in a tubeless type pneumatic tire, as shown in FIGS. 5 (a) and 5 (b), the innermost inner liner layer 1 has a thickness of 0%. .8-2
mm of butyl rubber as a main component, usually a brominated butyl rubber (Br-IIR) layer 1a and a natural rubber (N
At present, what is obtained by bonding the R) layer 1b is specially bonded. X is a tubeless type pneumatic tire, 3 is a ply coating rubber layer constituting a body ply material, and 4 is a steel cord.

On the other hand, in recent years, the overall performance of pneumatic radial tires has been improved, road conditions have been improved,
The use period of summer tires has been further extended due to stricter weight regulations and the like, and summer tires have been used for a long time. Under such circumstances, the current situation in FIG.
In the inner liner configuration shown in (a) and (b), the oxygen and moisture that would be included when air is filled into the pneumatic tire X are suppressed by the Br-IIR layer 1a. Only gradually enters the NR layer 1 b and the periphery of the body ply 3. However, with long-term use, oxygen and moisture that have passed through the Br-IIR layer 1a become NR
Absorbing and accumulating in the layer 1b steadily, the entry of moisture and oxygen into the body ply material 3 cannot be prevented, and tire failure due to cord breakage and adhesive breakage in a different form from conventional cases has occurred. For example, sudden and early CBU in rehabilitation
The tire may fail due to (cord break) or side swelling. When the moisture and oxygen in the rubber around these body plies were measured, it was found that they increased to such an extent that no corrosion of the ply material or adhesion failure occurred.

That is, it can be said that the current configuration of the inner liner layer cannot prevent the intrusion of moisture and oxygen for use of a tire for a long period of time and is causing a decrease in the durability of the tire. . As a simple prevention method, it can be dealt with by increasing the gauge of the butyl rubber layer, but there is a problem in that the productivity is lowered and the cost is significantly increased.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a body ply material without significantly changing the total thickness and productivity of the conventional inner liner layer. An object of the present invention is to provide a pneumatic tire provided with an inner liner layer that suppresses ingress of moisture and oxygen around the tire.

[0008]

Means for Solving the Problems The present inventor has conducted intensive studies to solve the above-mentioned problems, and as a result, in a pneumatic tire using a steel cord as a body-ply material, an inner inner side of the body-ply material was used. By making the liner layer have a specific structure, the pneumatic tire for the above purpose was successfully obtained, and the present invention was completed.

That is, the pneumatic tire of the present invention comprises:
(1) to (5). (1) In a pneumatic tire using a steel cord for a body ply material, the inner liner layer inside the body ply material has a low reactivity with gas and a matrix using a polymer having high gas permeability resistance as a matrix. A rubber layer and a gas trapping layer that has low gas permeability resistance and absorbs and traps gas to form a sandwich, and a gas intrusion preventing layer that prevents gas from invading into the body ply material by being laminated in a sandwich shape; A pneumatic tire characterized by the following. (2) The matrix rubber layer is made of butyl rubber, or halogenated butyl rubber, or a blend containing these butyl rubber as a main component, and the matrix rubber layer has a thickness of 0.4 mm to 1.2 mm. The pneumatic tire according to 1). (3) The gas trap layer is made of a rubber compound containing natural rubber as a main component, or a foamed rubber layer, or a water-soluble polymer absorbing water molecules, and the thickness of the gas trap layer is 0.6 mm or more. A pneumatic tire according to the above (1) or (2). (4) The thickness of the gas trap layer is 0.6 mm to 1.5 m
m. The pneumatic tire according to the above (1) or (3), wherein m is (5) The gas intrusion prevention layer, the matrix rubber layer and the gas trap layer are alternately stacked in a sandwich form by two to six sheets, and the air side serving as the innermost layer becomes the matrix rubber layer (1) to (4). A pneumatic tire according to any one of the preceding claims.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3, the same names and the like as those in the prior art [FIG. As shown in FIGS. 1 to 3, the pneumatic tire of the present invention is a pneumatic tire Y using a steel cord 4 for the body ply material 3.
The inner liner layer 10 inside is made of a matrix rubber layer A having a polymer of low reactivity with gas and high gas permeation resistance as a matrix, and a gas permeation resistance and low gas permeation resistance for absorbing and trapping gas. A plurality of strap layers B are laminated in a sandwich form to prevent gas intrusion into the body ply material 3;
It is applicable to a tubeless type or a tube type pneumatic radial or bias tire. In tubeless pneumatic tires,
The inner liner layer directly serves to maintain air pressure, and in a tube type pneumatic tire, serves to maintain air pressure with a tube interposed therebetween.

In the pneumatic tire of the present invention, the matrix rubber layer A is a matrix rubber layer in which a polymer having low reactivity with gas and high gas permeability is matrixed. The matrix rubber layer is composed of butyl rubber, halogenated butyl rubber such as chlorinated butyl rubber (Cl-IIR), brominated butyl rubber (Br-IIR), or a blend containing these butyl rubber as a main component. As the blend layer mainly containing butyl rubber, for example, butyl rubber, halogenated butyl rubber as a main component, and natural rubber (NR) or styrene-
A blend of butadiene rubber (SBR) and the like can be given. The thickness of this matrix rubber layer is 0.4
mm to 1.2 mm, preferably 0.5 mm to 0.8 m
m. When the thickness of the matrix rubber layer is less than 0.4 mm, the effect of suppressing moisture permeation is low, and when the thickness of the matrix rubber layer exceeds 1.2 mm, the effect of suppressing moisture permeation is saturated (this point). Will be further described in Examples and the like).

The gas trap layer B has a low gas permeation resistance and absorbs and traps a gas. The gas trap layer B actively absorbs a rubber compound layer containing natural rubber as a main component, a foamed rubber layer, or water molecules. It consists of a water-soluble polymer layer that absorbs.
As a rubber compound layer containing natural rubber as a main component, for example, natural rubber is filled with low reinforcing carbon black,
Compounds cross-linked with sulfur are exemplified. As the foamed rubber layer, for example, carbon black reinforcing filling NR
/ BR blend rubber foamed with DPT (dinitrosopentamethylenetetramine) -urea. Examples of the water-soluble polymer layer that positively absorbs water molecules include a compound in which a water-soluble resin such as polyvinyl alcohol is blended with a natural rubber-based compound. In the present invention, since the number of ABA sandwich units between the matrix rubber layer A and the gas trap layer B is increased as much as possible, the thickness of the gas trap layer B is based on (the total gauge of the B layer is assumed). The gas trap layer B has a thickness of 0.6 mm or more, preferably 0.6 mm or more.
１．５1.5 mm. The thickness of the gas trap layer B is 0.6
If the thickness is less than mm, the innermost layer is excessively deteriorated by oxygen, and cracks are generated. As a result, it becomes impossible to function as a gas trap.

In the pneumatic tire according to the present invention, the gas intrusion preventing layer (inner liner layer) for preventing gas from entering into the body ply material is formed by alternately forming the matrix rubber layer A and the gas trap layer B having the above-described structure in a sandwich manner. 2 to
Six pieces were bonded, and the air side, which was the innermost layer, was a matrix rubber layer. In the above description, “one to six sheets are bonded” means “one sheet” of a composite layer in which the matrix rubber layer A and the gas trap layer B are bonded.
As the gas intrusion prevention layer 10, for example, as shown in FIG. 2, a matrix rubber layer A and a gas trap layer B are alternately laminated in a sandwich form, or as shown in FIG.
For example, there is a case where four matrix rubber layers A and gas trap layers B are alternately laminated in a sandwich form. The reason why the air side, which is the innermost layer, is a matrix rubber layer is to suppress the permeation of moisture and oxygen from entering the matrix rubber layer, which is the first rubber layer. If the number of composite layers in which the matrix rubber layer A and the gas trap layer B are alternately sandwiched is less than two, penetration of moisture and oxygen into the body ply material will be prevented for long-term use of the tire. If it is not possible to prevent it, the durability of the tire will be reduced, and even if the number of tires exceeds six, the effect of the present invention will hardly change, but the cost will be increased, which is not preferable.

In the pneumatic tire of the present invention thus constituted, the inner liner layer is composed of a matrix rubber layer A having a matrix of a polymer having low gas reactivity and high gas permeability resistance, The gas trapping layer has a low gas permeability and is characterized by actively utilizing a layer having a different function and role from a gas trapping layer B for absorbing and trapping gas. Its operation mechanism is as follows. In FIG. 5A, which is a conventional configuration, oxygen and moisture to be charged into the pneumatic tire are suppressed from being transmitted through the A layer.
Only gradually enter the area around the B layer and body ply. However, the oxygen moisture permeated through the layer A is absorbed and accumulated more and more in the layer B over a long period of use. In the B layer, when compared with the A layer, one digit is higher in permeability,
While the crosslinked polymer is substantially uniformly accumulated and contained and contains multiple double bonds, in the case of the present invention, as shown in FIGS. the oxygen and moisture is once trapped in the layer to absorb oxygen and moisture that B layer, further to be suppressed transmission in the next layer a _2, mixed in _one layer B is forced high to B ₁ layer within It will be accumulated and contained. By repeating this action one after another between A ₂ -B ₂ -A ₃ or between A ₃ -B ₃ -A ₄ , the water and oxygen contents around the body ply are suppressed.

[0015]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Examples 1 to 4 and Comparative Example 1) A pneumatic tire having an inner liner layer having the contents shown in Table 1 below was produced, and the following test was carried out to determine the moisture content in the coating rubber near the body ply. The rate and oxygen concentration were measured. The results are shown in Table 1 below.

The test was conducted by injecting 300 ml of water into a tubeless type TBR of 11 / 70R22.5, applying a regular internal pressure, leaving the tire to stand in a constant temperature bath at 60 ° C. for three months, and then traveling 30,000 km under a regular load. The increase in the water content and oxygen concentration in the coating rubber near the body ply afterwards was measured in comparison with the original tire. Is separated as the amount spent from the degradation of).

FIG. 4 shows the relationship between the thickness of the matrix rubber layer A and the permeation of moisture into the body ply material. The gauge of the A layer is simply measured from 0.1 mm to 1.6 m.
FIG. 9 is a characteristic diagram showing the water permeability of the body ply coating rubber when the thickness is changed to m (the gauge of the layer B is fixed to 3 mm). As is clear from the results of FIG.
It has been found that when the thickness of the matrix rubber layer A is less than 0.4 mm, the effect of suppressing moisture is low, and when the thickness exceeds 1.2 mm, the effect of suppressing moisture is saturated.

[0019]

[Table 1]

(Consideration of Table 1) Example 1 is different from Comparative Example 1 in that the composition of the inner liner layers A and B is the same, and the total gauge of each layer is the same.
The effect of a two-layer sandwich type of a gauge in which the layer and the layer B are divided into two pieces and affixed to the inside of the body ply was confirmed. In comparison with Comparative Example 1, it was found that both the moisture content and oxygen in the body ply C / G could be reduced to almost half. In the second embodiment, (Ai-Bi
-Ai ...) By increasing the number of sandwich sets to four, it was possible to further reduce both the moisture content and oxygen by half. It was confirmed how effective it was to make the structure of the inner liner a sandwich type having two different functional layers as in the present invention. Next, Examples 3 and 4 are obtained by adding the effect of the composition in addition to the effect of the number of sandwich steps. In Example 3, water was trapped in the bubbles by using foamed rubber for the B layer, so that an increase in water could be suppressed. In Example 4, when the water-soluble polymer was contained in the layer B, it was possible to more positively suppress the increase in water content. As described above, as shown in Examples 1 to 4, by increasing the inner liner configuration as in the present invention, an increase in the body ply C / G moisture percentage can be achieved as compared with the conventional configuration using the inner liner of Comparative Example 1. It is possible to reduce it by half to 1/10, and the durability of steel radial tires during long-term use, especially CBU involving moisture and oxygen
(Cord breakage) and improvement of the adhesive breakage durability are possible.

[0021]

According to the present invention, in a pneumatic tire using a steel cord as a body ply material, it is possible to prevent moisture and gas from penetrating into the body ply material and to improve the durability of the pneumatic tire. Tires can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a pneumatic tire showing an example of an embodiment of the present invention.

FIG. 2 shows an example of a main part of the embodiment of the present invention, and is an enlarged partial sectional view of D in FIG.

FIG. 3 is a partial sectional view showing another example of FIG. 2;

FIG. 4 is a characteristic diagram showing the relationship between the thickness of a matrix rubber layer and the permeation of moisture into a body ply material.

FIG. 5A is a sectional view of a conventional pneumatic tire,
(B) is an enlarged partial sectional view of C in (a).

[Explanation of symbols]

 X, Y Pneumatic tire 1 Inner liner layer 3 Body ply material 10 Inner liner layer (gas intrusion prevention layer) A matrix rubber layer B Gas trap layer

Claims (5)

[Claims] 1. A pneumatic tire using a steel cord as a body ply material, wherein an inner liner layer inside the body ply material has a polymer having low reactivity with gas and high gas permeability resistance as a matrix. A gas intrusion prevention layer that prevents gas intrusion into the body ply material by adhering multiple layers of a matrix rubber layer and a gas trap layer that has low gas permeability resistance and absorbs and traps gas to form a sandwich. A pneumatic tire characterized in that: 2. The matrix rubber layer is made of butyl rubber, halogenated butyl rubber, or a blend containing these butyl rubber as a main component, and the thickness of the matrix rubber layer is 0.4 mm to 1.2 mm. The pneumatic tire according to claim 1. 3. The gas trap layer is made of a rubber compound containing natural rubber as a main component, a foamed rubber layer, or a water-soluble polymer absorbing water molecules, and the thickness of the gas trap layer is 0.6 mm. The pneumatic tire according to claim 1 or 2, which is as described above. 4. The gas trap layer has a thickness of 0.6 mm.
The pneumatic tire according to claim 1 or 3, which has a thickness of 1.5 mm. 5. The gas intrusion prevention layer comprises a matrix rubber layer and a gas trap layer which are alternately formed in a sandwich form.
The pneumatic tire according to any one of claims 1 to 4, wherein the air side, which is the innermost layer, is a matrix rubber layer.